Plastic, paper or cotton bag. What’s best?

PLASTIC: has a poor reputation because when it is littered, it is bad for wildlife [1], and degrades very slowly [2]. However, if we improve our reuse, recycling, and disposal of plastic [17], then plastic seems like a great option for many things due to its low carbon footprint [3].

PAPER: The carbon footprint of a paper bag is similar to, or greater than, that of a plastic bag [3,7]. However, since a paper bag is more likely to break, it will usually be re-used fewer times than a plastic bag [3].

COTTON: has a reputation as a great alternative to plastic [6]. Sadly, this idea is just a result of clever marketing [5]. Growing cotton requires vast quantities of water: ~2700 liters to make a t-shirt [9]. This causes huge water shortages, such as the drying of the 4th biggest lake in the world (the Aral Sea), which is now 10% of its original size [10]. Much of the lake was replaced by desert, causing pesticide-laden dust storms that cause throat cancer – this area has the highest rates of this disease in the world [9]. Organic cotton is made without using pesticides [3]. This is good for the farmers [11,12], but means the crop grows slower and needs more land, worsening the overall environmental impact [3,13]. Excluding littered plastic, the total environmental impact of a cotton bag is ~7100x worse than a thin plastic bag; organic cotton is ~20,000x worse [3]!

POLYESTER: needs much less water than cotton to be made [14]. It can be made from recycled plastics, and can itself be recycled, so should in theory should not require much new oil to be extracted [14]. However, polyester has a higher carbon footprint than cotton [15]. Plus, every time you wash it, microplastics are released into the water system, eventually polluting the ocean [14,18]. And, it cannot be coloured with natural dyes, meaning water pollution is worse [14].

So, it’s a complicated picture! In the end, the best way to save resources and the environmental harm caused in production, is to buy fewer things or to get them second-hand [16]. We will write about further alternatives like hemp in the future.